Wild Hosts and Biological Control of the Invasive Spotted Wing Drosophila
Horticultural Crops Research
2011 Annual Report
1a.Objectives (from AD-416)
1. Identify wild and ornamental hosts of spotted wing Drosophila (SWD) that serve as population reservoirs for infesting crop fields.
2. Test the effectiveness of predators for biological control of SWD.
3. Test the effectiveness of entomopathogenic nematodes for biological control of SWD.
1b.Approach (from AD-416)
Wild and ornamental fruit will be picked weekly from residential areas, roadsides, growers’ fields in the Mid-Willamette Valley. A subset will be exposed to SWD in 5 replicated lab cages under no-choice conditions to determine if SWD lays eggs and successfully develops on various fruits. SWD-infested potted fruit plants will be placed outdoors in sets of five and spaced at least 50 m apart among a larger agricultural field. Orius will be released at a zero (control), medium and high rate within potted plant sites, with ten replicate sites per treatment. After one week, the infested fruit will be dissected and reared out to determine survivorship of SWD. SWD larvae and pupae (loose within dirt or within fruit) will be exposed to nematodes to determine infection rates.
Drosophila suzukii is a serious threat to small fruit crops throughout the western United States. In addition to attacking a wide variety of crops, D. suzukii also infests non-cultivated wild fruiting plants. We have collected widely available wild hosts that have ripe fruit at collection periods, (June, July, or August) to determine the prevalence of naturally-occurring D. suzukii infestation in the field as well as compare the preference of each wild host to fruiting commercial crops in each of the three collection periods. D. suzukii readily infests a number of wild hosts in the field and in the laboratory. Understanding the preference of D. suzukii for various wild hosts will indicate which plants are key resources in the landscape and aid growers in determining if it is necessary to manage wild hosts bordering their crop fields.
The project was monitored by meetings, e-mail, and phone calls.